Science —

Blinded by the light

Sometimes it takes a sudden flash of inspiration to make science work

Sometime ago cosmologist started making measurements of how
galaxies rotated and they discovered an interesting problem.Galaxy rotation characteristics didn’t
correspond to the amount of luminous matter in the galaxy.More accurate measurement techniques allowed
researchers to pin down the amount of normal matter in galaxies quite
accurately, however, this still did not agree with the measured rotation
characteristics.After much debate, it
was decided that there must be some sort of matter that doesn’t interact with
electromagnetic forces (i.e., it can not glow), dubbed dark matter.Since then dark matter has become an
integral part of our description of how the universe evolved and evidence for
its existence has appeared everywhere, from galactic clustering to the
anisotropies of the cosmic microwave background. As has been noted here in the past not everyone finds dark matter a satisfying solution to the problem, and some consider it more a justification than a solution.

Thus it came as something of a surprise to Piers Forbes-Hamilton of the Keck observatory to find that the visible mass of galaxy an21250 exactly predicted its rotational characteristics. This is the first galaxy ever observed to have rotational behavior predicted accurately by gravitational calculations without the addition of dark matter and if it stands will be remembered as a landmark observation. The observation is so controversial that before announcing the discovery they had their results independently confirmed by other observatories.

This situation, where a galaxy's rotational behavior is exacly predicted by gravity - without additional dark matter - is completely unprecedented. These observations have been checked numerous times and we are confident that the data is good. However, this implies that our understanding of the big bang, gravity and dark matter are incorrect and will have to be revised.

This finding has completely shocked the physics community, with some calling it the greatest discovery in the last 100 years, and others calling for the telescope calibration to be checked. Such a finding implies that all the recent sky maps will have to be rechecked and perhaps performed again in order to recalculate the amount of ordinary matter in the universe. Particle physics too is affected, since many of the supersymmetry models predict the presence of dark matter, which may now not be neccessary. We live in interesting times.

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Chris Lee
Chris writes for Ars Technica's science section. A physicist by day and science writer by night, he specializes in quantum physics and optics. He Lives and works in Eindhoven, the Netherlands. Emailchris.lee@arstechnica.com//Twitter@exMamaku